The Calcasieu Ship Channel was closed for nearly 24 hours after a dredge pierced a sub-sea natural gas pipeline.
The accident involving the hopper dredge Bayport happened at 2030 on March 30 during dredging operations near buoy #28 about 12-nm south of Cameron, La., jetties.
The 303-foot vessel struck the pipeline causing a breach in the line and a visible fountain of natural gas and condensate at the water surface. The dredge was working under contract to the Army Corps of Engineers.
The dredge operator notified Stingray-Enbridge, the pipeline owner, said Terri Larson, a spokeswoman at the Houston-based company. She said the dredge equipment had struck a "12-inch lateral pipeline in the WC 62 block on Enbridge's Triton gathering system, approximately 12 miles offshore."
The U.S. Coast Guard immediately established a two-mile safety zone. A broadcast notice urged mariners to proceed with caution when transiting the area. The captain of the port closed the Calcasieu Ship Channel to all traffic as of 2142.
The leak involved product from El Paso Exploration and Production's Platform A in West Cameron block 62, about 1-nm east of the accident site. It was quickly shut down to prevent further release of condensate and natural gas through the ruptured pipeline, said Coast Guard spokesman Richard Brahm.
Platform A operators noted a slight drop in pressure in their discharge line. It was shut in at about 2200.
"Initially, there was concern that the downstream check valve in the line was not holding, causing back pressure from the other platforms and lines that feed the main trunkline," the Coast Guard said in a press release. The check valve held, however.
Stingray-Enbridge mobilized personnel and skimmers for cleanup. Oil spill recovery resources were activated through Clean Gulf. The Coast Guard monitored the situation with helicopters and on-scene inspection crews.
Once a dive team from Stingray-Enbridge secured the damaged pipeline and engineers determined that it posed no threat to deep-draft vessels, Calcasieu Ship Channel was reopened March 31, Brahm said. The safety zone was rescinded after sonar scans of the pipeline indicated that the channel was clear of protrusions.
No visible signs of pollution were found following the repair. The Coast Guard estimates the spill volume as less than 60 barrels of sheen producing condensate. Stingray-Enbridge is awaiting permit approval from the Army Corps to begin permanent repairs on the pipeline.
Manson Construction Co., the dredge's owner, did not respond to a request for comment.
The Coast Guard and the Bureau of Ocean Energy Management, Regulation and Enforcement are investigating the cause of the incident.